Pile hammer



April 18,4944. l* G. BELL. f

. PILE HAMMER Filed sept. les,v 1.942

Patented Apr. 1S, 1944 PILE HAMIMER Noel Gonne Bell, London, EnglandApplication September 16, 1942, Serial No. 458,590 In Great Britain July7, 1941 2 Claims.

rThis invention relates to the type of pile-driving hammer thatcomprises a stationary piston, a cylinder reciprocable vertically withrespect to the piston to form the hammer striking ram, and a valveassociated with the piston to control the admission and exhaust ofmotive fluid to and from the cylinder as required alternately to raisethe cylinder and allow it to fall by gravity.

Pile driving hammers of the aforesaid type have the characteristic thata high `proportion of their total weight is in the ram, i. e. thecylinder.

Objects of the invention are, firstly, to provide a pile-driving hammerwith the above mentioned characteristic maintained o-r enhanced and withimproved and simplified means for bringing about the automatic operationof the control valve on reciprocation of the cylinder and, secondly, theprovision of means for the said purpose such that it is completelyprotected from damage when the cylinder is at rest in its lowerposition, i. e. its position when pitching piles or transporting thehammer and, thirdly, to provide a construction such that the motivefluid does not exert upward pressure on the stationary element, i. e.the .piston (which it is a main object of the invention to make as lightas possible), and cause it to bounce on the pile.

Accordingly the invention provides a pile-driving hammer comprising, incombination, a holy low piston having upper and lower verticallyextending hollow piston rods, a cylinder reciprocabie relatively to thepiston to form the hammer striking ram guided by the piston rods, avalve turnable within the hollow piston and having angularly spacedfacing members engaging the inner surface of its peripheral wall, thesaid wall having admission and exhaust ports opening through the saidinner surface and leading respectively to the cylinder space above andbelow the piston, means for supplying motive .fluid to the hollow pistonthrough the upper hollow p-iston rod, and means disposed wholly belowthe piston to turn the valve automatically on reciprocation of thecylinder alternately to open the If desired, there may be sets oflinearly spaced cam ramps, the spacing of the cam ramps in the said setsbeing different in order to enable the hammer stroke to be variedaccording to which set is utilised, that is with which set the memberprojecting from the cylinder selectively co-acts.

Further, the cam rod may be accommodated in the piston rod below thepiston, the piston rod being hollow to accommodate it, and the cam rodhaving a cam groove (or cam grooves) presenting cam ramps (or sets ofcam ramps) as aforesaid, the piston rod also having an axial groove (orgrooves) for the passage of the .projecting cylinder member intoco-acting sliding engagement with the cam groove (or a selected one ofthe cam grooves).

By way of example a pile driving hammer ernbodying the aforesaid andother features of the invention is illustrated on the accompanyingdrawing to which reference will now be made.

Fig. l is an elevation of the hammer partly in section.

Fig. 2 represents, on a larger scale, a quarter Sectio-n through thepiston and valve in the plane II-II of Figs. 5 and 6, the valve being inthe admission position; all four quadrants are identical.

Fig. 2c', is a view similar to Fig. 2 but showing the valve in theexhaust position.

Fig. 3 is a sectional top plan of one quarter of the piston in the planeIII- 111 of Figs. 5 and 6.

Fig. 4 is a sectional bottom plan of one quater of the piston in theplane IV-1V of Figs. 5 and 6.

said admission ports to the supply of motive .fluid and to the saidexhaust ports.

Preferably the said means comprises a cam rod situated below the pistonand engaging the control valve at its upper end and presenting linearlyspaced cam ramps corresponding to admission and exhaust positions of thevalve, in combination with at least one member projecting inwards fromthe cylinder into sliding engagement with the cam rod.

Fig. 5 represents, in vertical section in the plane V-V of Fig. 2u, halfof the piston and valve'and shows how the admission ports open to thecylinder space above the piston.

Fig. 6 represents, in vertical section in the plane VI-VI of Fig. 2a,half of the piston and valve and shows how the exhaust ports o-pen tothe cylinder space below the piston.

Fig. '7 represents a part section through the hammer in the planeVII-VII of Fig. 1.

Fig. 8 represents a section through the lower piston rod and cam rod cfamodification.

iFig. 9 represents an elevation of the cam rod showing the cam grooveand ramps.

Referring now in detail to the drawing, ifdenotes the hammer cylinder, 2the piston, 3 the lower hollow piston rod that extends through thekbottom of the cylinder and is adapted to rest on the pile to be driven,and t the upper hollow piston rod that extends through agland' in thecylinder `cover 6. The motive fluid is supplied lto the hammer throughthe upper piston rod-1.

As bestshown by Figs. 5 and -6, the piston 2 is cupped or recessed tohouse an oscillatory control valve hereinafter referred to, the recessbeing closed by a cover plate 'I secured in position by bolts 8 (Fig.3). The lower end of the upper hollow piston rod 4 is secured to thiscover plate, and the upper end o-f the lower piston rod 3 is secured ina central opening formed in the base of the piston 2.

The piston 2 itself constitutes the valve casing, to which the motivefluid is supplied by way of the upper piston rod 4, and has in itsperipheral wall a series of adjacent admission and exhaust ports 9 andI0 respectively. In the embodiment illustrated there are four pairs ofsuch ports, but the number may vary according to the size of the hammerand the port area required for its effective operation. All of the portsopen through the inner surface of the peripheral wall of the piston(Figs. 2 and 2a), and each of the admission ports S opens to thecylinder space above the piston (Fig. 5) while each of the exhaust portsI opens to the cylinder space below the piston (Fig. 6).

The oscillatory control valve comprises a hub member II journalled inthe upper end of the lower piston rod 3 and presenting, within theaforesaid valve casing, spider arms I2, and a facing member I3 slidablyembracing each such arm. There are as many facing members as there arepairs of ports 9, I Il, i. e., rour in the illustrated embodiment. Thehub member rests on a ball thrust bearing I4; if desired, a ball thrustbearing may also be interposed between the shoes and the piston coverplate 'I in case of rebound of the piston due to the hammer blows. Thearcuate surface of each facing member, which in the illustrated form ispressed into huid-tight engagement with the inner peripheral surface ofthe piston by the motive fluid supplied to the valve casing (theinterior of the piston), has a transfer duct I3a for a purposehereinafter described.

Operating mechanism for the oscillatory control valve comprises a camrod i (Figs. 5, 6 and 9) engaging the valve member Il and supportedwithin the lower hollow piston rod 3, and a member I (Figs. 1 and 7)projecting radially from the cylinder I through a vertical slot I'I inthe said lower piston rod into engagement with a cam groove IB formedinthe cam rod. The groove I8 presents an admission cam surface 0r ramp2i) and an exhaust cam surface or ramp I9 such that as the member I6moves vertically up and down with the cylinder I the cam rod is turnedto and fro. The upper end of the cam rod and the lower end of the valvemember Il are connected by dog teeth in engagement as appears from Figs.4 to 6, so that the turning movements imparted to the cam rod aretransmitted to the valve. The lower end of the cam rod is supported by abush or collar 22 within the lower piston rod as shown in Fig. l.

With the hammer cylinder or ram I at the bottom of its stroke (Fig. 1)and the lower piston rod 3 resting on a pile to be driven, the aforesaidoscillatory valve Il, I2, I3 is in admission position, the facingmembers I3 being disposed to uncover the admission ports 9 and cover theexhaust ports Il) (Figs. 2 and 5). Il. now the supply of motive fluid tothe upper piston rod li is turned on, the fluid will pass from the valvecasing, i. e. the recess in the piston 2l, through the ports 9 into thecylinder space above the piston to raise the cylinder. On the upwardstroke of the cylinder the ,member VIt engages -the exhaust cam surfaceor ramp I9 and turns the valve to the "exhaust position in which thetransfer ducts I3a in the valve facing members I3 (see Figs. 2a and 6)connect the admission ports 9 with the exhaust ports I6 whereby thefluid in the cylinder space above the piston passes to the cylinderspace below the piston and then escapes by way of outlet ports 2|provided in the lower part of the cylinder. In consequence the cylinderfalls by gravity to deliver a blow on the pile. As the falling cylinderapproaches the end of its stroke the member I6 engages the admission camor ramp 2l) and resets the valve whereupon the operative cycle isrepeated automatically until the supply of motive fluid to the valvecasing is turned off.

, To enable the hammer to be employed for extracting piles there may, asshown in Fig. `8, be a second cam groove Ia in the cam rod havingeXhaust" and admission cam ramps disposed at lower and higher levelsrespectively than in the cam groove I8 so as to bring about short upwardstrokes of the cylinder and cushioned downward blows.

The cam groove ISa can be brought into use by removing the member I3(Fig. 7), turning the cam rod to bring the cam groove IBa into alignmentwith the vertical slot Il' in the lower piston rod 3 and thenre-inserting the member I6.

Other constructional modifications may be made within the scope of theinvention. For instance, the members I3 affording the valve faces may berigidly attached to or made integral with the rest of the valve, therebyto reduce torque due to sliding friction and to enable the diameter ofthe valve to be reduced, if desired; the lower piston rod 3 may beexternally square or oval in cross section to prevent the cylinder orram I turning on the piston and to ease the stress on the member I6.

A pile driving hammer constructed as hereinbefore described offers theadvantages that the valve is fully automatic in action and is at alltimes totally enclosed and protected from damage, and that a smallmovement of the cam rod is sufficient to bring about a larger movementof the valve facing members thereby to delay admission of the pressurefluid and avoid cushioning of the hammer blow. At the same time theknown advantages of the type of hammer to which the invention appliesare enhanced, namely, the high proportion of the total hammer weightconcentrated in the cylinder or ram and economical use of the motivefluid with increased silence due to the fluid exhausting from the upperto the lower part of the cylinder. It is also evident from Fig. 1 thatwhen the cylinder is at rest in its lower position, which is itsposition when pitching piles or when transporting the hammer, the valveoperating mechanism is completely housed within the cylinder and thusfully protected from damage.

I claim:

1. A pile-driving hammer comprising, in combination, a hollow pistonhaving upper and lower vertically extending hollow piston rods, acylinder reciprocable relatively to the piston to form the hammerstriking ram guided by the piston rods, a valve turnable within thehollow piston and having angularly spaced facing members engaging theinner surface of its peripheral wall, the said wall having admission andexhaust ports opening through the said inner surface and leadingrespectively to the cylinder space above and below the piston, means forsupplying motive fluid to the hollow piston through the upper hollowpiston rod, and means disposed Wholly below the piston to turn the valveautomatically on reciprocation of the cylinder alternately to open thesaid admission ports to the supply of motive fluid and to the saidexhaust ports.

2. A pile-driving hammer as claimed in claim 1, the said means forautomatically turning the valve comprising a cam rod supported withinthe lower hollow piston rod and presenting at least one cam groove Withlinearly spaced cam ramps corresponding respectively to admission andexhaust positions of the valve, and at least one member projecting fromthe cylinder through a groove in the lower piston rod into slidingengsi-gement with the said cam groove.

NOEL GONNE BELL.

